The present invention relates to a vehicular electronic key system for unlocking/locking doors and starting an engine. The electronic key system includes an electronic key and an on-vehicle apparatus which communicate with each by means of wireless communication and identify ID (identification data) therebetween to permit the door unlocking/locking operation and the engine starting operation.
A Japanese Patent Provisional Publication No. (Heisei) 11-36675 discloses a vehicular electronic key system which executes unlocking door according to an identification result between a first ID code of an electronic key and a registered ID code and executes starting an engine according to an identification result between a second ID code sent of the electronic key and another registered ID code.